Eriocheir sinensis

Geographic Range

Chinese mitten crabs are found on coasts from Japan to the mainland of China, Korean Peninsula, and along the Yellow Sea; they are also found on the coasts of northern and eastern Europe and the United States.

• Biogeographic Regions
• nearctic nearctic
  • introduced introduced
• palearctic palearctic
  • introduced introduced
  • native native

Habitat

Chinese mitten crabs spend most of their lives in brackish water and freshwater rivers and estuaries. Eriocheir sinensis migrates downstream to saltwater environments to reproduce. During migration they are known to cross terrestrial boundaries, but they do not spend much time on land.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• rivers and streams
• coastal coastal
• brackish water brackish water

Physical Description

Chinese mitten crabs are light brown and have hairy claws that are typically white-tipped, giving the appearance of mittens. They have a notch between the eyes and 4 lateral carapace spines. Their legs are generally twice as long as the width of the carapace, which has an average maximum width of 80 mm. Males and females are dimorphic: males have a V-shaped abdomen whereas the females have a U-shaped abdomen.

• Other Physical Features
• ectothermic ectothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes shaped differently

Development

After the fertilized eggs hatch, they are called zoea and do not look like adults. Zoea have a long dorsal spine, a rostral spine, and 2 lateral spines. They develop appendages on their side that will eventually be involved in feeding. In this stage, they spend 1 to 2 months in brackish water before migrating upstream for further development. After 5 zoeal stages, the crab undergoes metamorphosis from the zoeal stage to a megalopal stage. At this stage, the larvae begin to look like adults but are still distinguishable from them because of the presence of a protruding abdomen. After about 7 days in this stage, molting occurs and juvenile crabs emerge; they then migrate upstream and go on to develop into adults, where sexual maturity is reached between their fourth and fifth years of life.

• Development - Life Cycle
• metamorphosis metamorphosis

Reproduction

During the summer months mature Chinese mitten crabs begin their migration to the sea, with males arriving first and females arriving afterwards. Soon after reproduction, however, both sexes die and the progeny are left to fend for themselves.

• Mating System
• monogamous monogamous

Males and females come in contact and after initially fighting, mating behavior begins. During physical contact, males are able to recognize reproductively active females because the females release contact pheromones; they are only released after physical contact has been made.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Females aerate their eggs after they are fertilized so that nutrients can be passed from mother to baby. Females can produce anywhere between 250,000 to 1 million eggs, depending on the size of the female. After eggs have been fertilized, they are released about 1 day after mating and females then produce a substance that allow her eggs to adhere to part of her abdomen. Over the winter season, the females stay under deep water while the eggs develop.

• Parental Investment
• pre-hatching/birth
  • provisioning
    • female

Lifespan/Longevity

There are varied reports as to the lifespan of this species. Factors influencing the lifespan include temperature of the water, salinity, and others. Reports vary from lifespan as little as 1-2 years to as much as 3-5 years, depending on the region in which the crabs are located.

Behavior

Eriocheir sinensis is catadromous: adult Mitten Crabs live in fresh water, but migrate to salt water for reproduction. It is not clear how the crabs communicate during their migration, but it is speculated that there is an environmental cue, which triggers the migration. They are adept walkers and during migration are able to walk on banks and over other obstacles when needed. The offspring are also motile – as the zoea develop in the salt water, they gain the morphologic characteristics of the adult. Legs are developed which allow the juvenile crab to migrate upriver towards brackish water and finally to fresh water environment.

In fresh water the juvenile crabs burrow into the banks in order to escape predators and desiccation. Burrows are more extensive in tidal areas because when tide is low threats are greater.

• Key Behaviors
• terricolous
• motile motile
• migratory migratory
• social social

Communication and Perception

A study on mating communication shows that mate recognition occurs only after physical contact. The study indicates that once physical contact is established, a contact pheromone is involved.

• Communication Channels
• tactile tactile
• chemical chemical

• Other Communication Modes
• pheromones pheromones

• Perception Channels
• visual visual
• tactile tactile
• chemical chemical

Food Habits

Mitten Crabs are omnivores, which means that they eat both plants and animals as its primary food source. As juveniles they mostly eat vegetation but also prey on small invertebrates

• Primary Diet
• omnivore omnivore

• Animal Foods
• other marine invertebrates

• Plant Foods
• algae

• Other Foods
• detritus detritus

Predation

Mitten Crabs are subject to predation by many carnivorous organisms in the water and on land, including fish, frogs, and birds.

Ecosystem Roles

Mitten crabs are prey for many animals. They are also a secondary intermediate host of the Oriental lung fluke -- Paragonimus ringeri . Mammals including humans are the final host of this parasite. Mitten crabs can tolerate a wide range of environmental conditions. This is evident as this species has been spread via shipping to North America as well as Europe. When they are introduced to a new environment, their population becomes very large very fast and they change the structure of the local environment. For instance during migration, mitten crabs burrow into sediment and this increases erosion that can lead to collapse of river banks. They may also have a profound effect on biological communities through predation and competition.

• Ecosystem Impact
• creates habitat
• soil aeration soil aeration

Economic Importance for Humans: Positive

Mitten crabs are a delicacy in Asia and other places. They can be used as bait for eel fishing, in the production of cosmetic products, and as fertilizer in agriculture.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

When the mitten crabs invade, they can damage the riverbanks because of their burrowing behavior as mentioned in the Ecosystem Roles section. This could be a financial problem if development along the riverbank is threatened. Mitten crabs cause damages to commercial fishing nets. They could also eat the trapped fish in commercial ponds. Crabs damage crops in China by consuming rice shoots. Humans can become infected with Paragonimus ringeri by eating poorly cooked or raw mitten crabs.

• Negative Impacts
• injures humans
  • causes disease in humans causes disease in humans
• crop pest

Conservation Status

Eriocheir sinensis is not vulnerable, threatened, or endangered on any part of its native or introduced range.

Additional Links

Encyclopedia of Life

Contributors

Anna Solovyeva (author), Rutgers University, Kyle Bailey (author), Rutgers University, David Howe (editor, instructor), Rutgers University .

References

Clark, P., B. Hemsley-Flint. 2007. "Eriocheir Sinensis" (On-line). Accessed October 13, 2007 at http://www.jncc.gov.uk/page-1709 .

Gollasch, S. 2006. "Eriocheir Sinensis (Crustacean)" (On-line). Accessed October 13, 2007 at http://www.issg.org/database/species/ecology.asp?si=38&fr=1&sts= .

Herborg, L., M. Bentley, A. Clare, K. Last. 2006. Mating Behaviour and Chemical Communication in the Invasive Chinese Mitten Crab Eriocheir sinensis. Journal of Experimental Marine Biology and Ecology , 329: 1-10. Accessed October 13, 2007 at http://web2.uwindsor.ca/courses/biology/macisaac/pages/JEMBE.pdf .

Metzler, J. 1998. "Chinese Mitten Crab (Eriocheir Sinensis)" (On-line). Accessed October 13, 2007 at http://www.iisgcp.org/exoticsp/Chinese_Mitten_Crab.htm .

Rainbow, P., R. Roni, P. Clark. 2003. Alien invaders: Chinese mitten crabs in the Thames and spreading. Biologist , Volume 50/Issue 5: 227-230. Accessed October 31, 2007 at http://web.ebscohost.com/ehost/pdf?vid=5&hid=5&sid=497b8b4e-4eeb-4a84-9500-8dd7e22cd466%40sessionmgr7 .

Robbins, R., P. Clark, P. Rainbow. 2007. "Mitten Crabs: Oriental Invaders of the River Thames" (On-line). Accessed October 13, 2007 at http://www.nhm.ac.uk/nature-online/life/other-invertebrates/chinese-mitten-crabs/chinese-mitten-crabs.html .

1998. "Chinese Mitten Crab: Life and History" (On-line). Accessed October 13, 2007 at http://www.delta.dfg.ca.gov/mittencrab/life_hist.asp .

2003. "Eriocheir Sinensis (Milne Edwards, 1853)" (On-line). Accessed October 13, 2007 at http://nis.gsmfc.org/nis_factsheet.php?toc_id=132 .

2007. "Mitten Crab Projects" (On-line). Accessed October 13, 2007 at http://www.clr.pdx.edu/projects/ans/mittencrab.php .

Aquatic Nuisance Species Task Force. National Management Plan For the Genus Eriocheir (Mitten Crabs). 2003. Accessed November 09, 2007 at http://www.anstaskforce.gov/control.php .